Background Childlessness increases the risk of premature mortality and psychiatric illness. These results might, however, be confounded by factors that affect both the chance of parenthood as well as the risk of premature death and psychiatric illness.

Methods Using population-based health and social registers, we conducted a follow-up study of 21 276 childless couples in in vitro fertility treatment.

Results The crude death rate ratio in women who become mothers to a biological child is 0.25 (95% CI 0.16 to 0.39). In other words, childless women experience a fourfold higher rate of death, that is, 4.02 (2.56 to 6.31). The analogous death rate in fathers is approximately halved: 0.51 (0.39 to 0.68) and 0.55 (0.32 to 0.96) associated with having a biological child and an adopted child, respectively. With substance use disorders being the exception, none of the crude rates of psychiatric illness in parents of a biological child were statistically distinguishable from the rates in the childless. These findings were slightly confounded by age, calendar year, income, education, somatic comorbidity and marital breakup.

Conclusions Mindful that association is not causation, our results suggest that the mortality rates are higher in the childless. Rates of psychiatric illness do not appear to vary with childlessness, but the rate of psychiatric illness in parents who adopt is decreased.